Molecular Weight Control via Cross Metathesis in Photo‐Redox Mediated Ring‐Opening Metathesis Polymerization. (24th March 2020)

• Record Type: Journal Article
• Authors: Kensy, Victoria K.; Tritt, Rachel L.; Haque, Farihah M.; Murphy, Laura M.; Knorr, Daniel B.; Grayson, Scott M.; Boydston, Andrew J.
• Is Part Of: Angewandte Chemie. Volume 132:Number 23(2020)
• Page Start: 9159
• Page End: 9164
• Publication Date: 2020-03-24
• Subjects: chain transfer -- cross metathesis -- functional polymers -- photoredox catalysis -- ROMP; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202000434
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Photo‐redox mediated ring‐opening metathesis polymerization (photo‐ROMP) is an emerging ROMP technique that uses an organic redox mediator and a vinyl ether initiator, in contrast to metal‐based initiators traditionally used in ROMP. The reversibility of the redox‐mediated initiation and propagation steps enable spatiotemporal control over the polymerization. Herein, we explore a simple, inexpensive means of controlling molecular weight, using alpha olefins as chain transfer agents. This method enables access to low molecular weight oligomers, and molecular weights between 1 and 30 kDa can be targeted simply by altering the stoichiometry of the reaction. This method of molecular weight control was then used to synthesize a functionalized norbornene copolymer in a range of molecular weights for specific materials applications. Abstract : Recycle, reuse, and reduce : By introducing a chain transfer agent capable of photoredox‐mediated and metal‐free cross metathesis, molecular weight control is extending into oligomeric regimes. The vinyl ether initiator is also rendered catalytic in nature, achieving effective initiator efficiencies >100 %.